Method of manufacturing reinforced air-tubes.



J. W. BLODGETT. METHOD 0F MANUFACTURING RE|NFORCED AIR TUBES.

APPLICATION FILED DEC. 4. I9|4A Patented Dec. 7, 1915.

.mnu w. nnonen'rr, or CHICAGO, rLLINoIs.

nn'rnon or luanureo'runrnennrnrononn arnfrunns.

Specification of Letters Patent.

Eatented Dec. 7, i915.

Original application led July S, 1913, Serial No. 778,00. *Divided and this application led December 4, 191e. Serial No. 875,430.

Be it known that I, JOHN VV'. Bnoncn'rfr, a citizen of the United States, and a. resident of Chicago, in the county of Cook and State of lllinois, have inventedcertain new and useful improvements in vMethods-of Manufacturing Reinforced Air-Tubes, of which the following is a. full, clear, and exact specification.

Myvinvention is concerned with. a novel method of making reinforced air tubes'for pneumatic tires of the character shown in my application,No- 778,040, filed July 9, 1913, of which the present applicationis a division.- y

As inner or air tubes have been constructed prior to my invention, they have been made of rubber unreinforced, with the result that once they become punctured 'under a heavy pressure, the tendency to tear the. rubber and thus enlarge the puncture is unresisted save by the strength of the rubber, which, for a thin flexible air-tube, is necessarily limited. Furthermore, the un'- reinforced rubber, after it has been cured a certain length of time, loses its life or becomes rotten, so tliatit is readily punctured, torn or blown out. j

4in my invention, I reinforce the air tube by embedding therein a tubular annulus of a loosely meshed fabric, preferably knitted, so that the fabric, owing to its loose mesh, can expand and contract :with the rubber as the tube is inflated or deiated. This reinforcement serves to make punctures less frequent and blow-outs more difficult, and also to' prevent their enlargement once they are made,and it also serves to give longer life to the tube, as the reinforced rubber, as it be# comes more or less rotten will resist a puncture or blow-out much longer than would -a similarly rotted and unreinforced tube.

similar view as it appears completed; Fig.

l is' alongitudinal section through the same Ion a'- smaller scale. asit appears 'du-ring the .process of'manufacture before the ends of the.knitted-fabric' tube' are joined; Fig. 4: is a top plan view of the same, iiattened as ber.

it appears 'in Fig. l, showing how the joint 1s formed in the fabric and how the valve is inserted; Fig. 5 is a view in section on the be employed in the manufacture of my im` Vproved air tube; and Fig. 8 1Sv a sectional view of a coating apparatus, which also may be employed .in carrying out my invention.

In carrying out my invention, I first place a layer of raw rubber of a line quality upon a hollow curing' mandrel, forming a tube of the uncured rubber on the mandrel, after which 'the uncured rubber is wrapped firmly on the mandrel with a wrapper so as to hold it tightly against the same while it is being cured. l then admit the proper amount of steam to the interior of themandrel, which, of course, will be provided with the necessary cocks to control the admission of the stealn and itsY escape from the mandrel and the rate at which. it passes through the same so as to control the heat imparted to the rub- A sufiicient degree of heat is applied to the mandrel for a sufiicient length of time to thoroughly cure the inner surface of the rubber invcontact with the outer surface of the. mandrel, but not enough to cure the outer surface of the rubber, which is protected by the wrapping. This results in producing a thin tube, the inner surface of which is cured, while the outer surface ,is raw or only partially cured. This portion of the lcompleted tube is indicated in the drawings 'by the reference character a.. Over this partially cured tube. I place a layer b of raw rubber, thick enough completely to embed the reinforcing fabric hereinafter dcscribed,l and this layer of raw rubber will, of course, be of uniform thickness through'- out, and may be of a quality inferior to that employed in making the inner portion a. After the tube has been thus far completed, the reinforcing fabric c is placed on the same. and it may be placed on the tube while it is still on the mandrel, and l preferably form this fabric by knitting it in the form of ,a tube very loosely over the mandrel. This fabric, when l employ my method in making air tubes. is knitted very loosely, so that it cau be expanded under pressure, and contract automatically withthe infolding rubber when the pressure is reon the tubes surrounding the mandrel n may be regulated by the helically-coiled expanding springs r surrounding theV bolts between the plate p and the nuts s threadedon said bolts. The valves 0l of course project up through suitable apertures t, indicated in dotted lines in Fig. `7, which apertures are formed in the plate p.' The tube or tubes thus held -under pressure are heated sufficiently to soften, but not cure the rubber, so, that the telescopedr parts yWill be thoroughly joined. In case the outer coating of raw rubber v is to I'be applied inthis modified process, the coating of raw rubber may be applied before the tubesare cured in the samey manner as set out in the previous description of the preferredmethod of forming the tubes. When the raw rubber is all added and the fabric frictioned by the pressure above described,l thetube is cured in the customary manner.

Vhile Ifhave shown-and described my in- Vention as carried out by the steps which I at present consider best ladapted to secure the desired results, `it Will be understood that it is capable of modifications, and that I do not desire to be limited inthe interpretation of the 'following claims, except as may be necessitated bythe state of the prior art.

What I claim as new, and. desire to secure by Letters Patent of the Unlted States, is:

1. The process of manufacturing a reinforced air tube, which consists incuring the inner surface only of a rubber tube by the application of curing heat to the inner surface only; in covering the uncured outer surface of the tube With a layer of raw rubber; in placing over the said raw rubber a loosely meshed fabric; and in finallyv subjecting the tube to pressure and heat so that the raw rubber will first pass through the meshes -of the fabric and then subsequently be cured to the outer surface of the initial tube, leaving the fabric completely embedded in completely cured rubber.

' 2. The process of manufacturing a reinforced air tube, which consists in curing the inner surface only of a rubber tube by the application of curing heat to the inner surface only; in covering the uncured outer surface of the tube With a layer of raw rubber; in placing over the said raW rubber a loosely meshed fabric; -in forming over the fabric tube a raw rubber tube; and in finally subjecting the tube to pressure and heat so that the raur rubber will first pass through the meshes of the fabric and then subsequently be cured to the outer surface of the initial tube, leaving the fabric completely 4embedded in completely cured rubber.

In Witness whereof, I have hereunto set my hand and aiiixed my seal, this thirtieth day of September, A. D. 1914.

JOHN WfBLODGETT.

Witnesses:

J oHN HOWARD McELnoY, MILDRED ELsNEn. 

